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Date of last update: 10/17/2017.

Forum Name: Endocrinology Topics

Question: IGF-1 level and Growth Hormone/Weight Gain

 pseudowise - Tue Jul 06, 2010 5:41 pm

Is it possible to have a high IGF-1 level and still have extreme weight gain? I am an adult (32 year old female), and in the last two years I have been diagnosed with hypothyroidism, iodine deficiency, pituitary adenoma/prolactinoma, and recently had some IGF-1 testing because we thought maybe there was a problem with growth hormone production. My result was 339 and the reference range was 64-334. I have gained 110lbs in the last two years. I do NOT overeat and I try to stay active despite problems with fatigue. The thyroid hormone and iodine supplementation have slowed the weight gain down only a little. I just started (just took my 2nd dose) Dostinex for the prolactinoma. Currently my doctor is on vacation and won't be back until the end of July, so I am left wondering what could be causing all of this until she gets back. I figured it wouldn't hurt to ask. So, basically, I am asking if there could still be a growth hormone problem even though the IGF-1 was elevated.

 pseudowise - Thu Jul 15, 2010 6:59 pm

Also, I have been tested for Cushing's multiple times and my cortisol is always normal.
 Dr.M.Aroon kamath - Sat Jul 17, 2010 6:21 am

User avatar Hi,
Thank you for your post. Human growth hormone's effects on body weight is mainly by increasing muscle mass and by increasing bone growth(during the growth phase). It causes breakdown of fat(lipolysis).

To make it more comprehensible, let me first provide information about what is popularly termed the "growth hormone-insulin-like growth factor (GH-IGF) axis" and its relevance to your query.

Growth hormone is produced by the pitutary gland under the influence of the hypothalamic hormones-GH-releasing hormone(GHRH) and somatostatin. GH stimulates the liver to produce IGF-1, IGF-2 and IGF-binding proteins(IGF-BP). IGF's can also be produced peripherally in various tissues via na autocrine or paracrine mechanism.

IGF-1 blood levels are used by clinicians as a screening test for growth hormone deficiency and excess(as in Acromegaly and Gigantism).

The levels of GH and IGF-1 in the circulation have been seen to vary considerably.To complicate it further, interpretation of IGF-1 levels display wide normal ranges.

Factors that are known to cause variations in the blood levels of growth hormone (GH) and IGF-1 include:
- age, sex, race, genetic make-up, stress levels, the time of day, nutritional level,exercise status, disease states, estrogen status and body mass index (BMI).Many of the hormones including sex hormones also influence the GH-IGF axis.

In recent years, xenobiotic intake is being talked about as a factor influencing GH-IGF status.

Thus, the first (and perhaps, crucial) question that should be answered in your case is whether your body fat is the main contributor for your excess weight or your muscle mass. If it happens to be the fat, then GH excess as a cause becomes less likely.The very minimal elevation of IGF should be interpreted with caution(as explained above).

I note from your profile that you have Ehlers-Danlos Syndrome(belongs to a group of rare genetic disorders caused by a defect in collagen synthesis). A number of research studies on the effects of human growth hormone in Ehlers-Danlos Syndrome have been conducted in the hope of finding any beneficial effects on the collagen bundles and elastic tissue fibers. Results so far, have not been encouraging.

I feel that you should take guidance from an endocrinologist who can assess you first hand and plan further workup as deemed necessary.
Best wishes!

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